The 6-foot-5 point guard, expected to be selected in the top three of June's NBA draft, said after Friday night's 86-75 loss to Kentucky in the NCAA tournament's Sweet 16 that he is heading to the NBA.
"That was my final game for UCLA, and I appreciate all the fans and all the support," Ball said.
Ball and his father, LaVar, had made no secret of the fact that he was one-and-done in Westwood. He averaged 14.7 points and 7.6 assists per game this season but finished his college career with a 10-point, 8-assist performance in the loss to the Wildcats. He was outdueled by Kentucky's De'Aaron Fox, who scored 39 points.
Ball said he felt bad that he couldn't carry his team's seniors to another win in the tournament and that UCLA had simply lost to a good team.
UCLA coach Steve Alford said he wasn't surprised by Ball's decision, even saying he assumed it was the end of the freshman's college career.
"I probably don't like to assume anything, but he's pretty good," Alford said.
He noted that there is a different culture in college basketball than during his playing days at Indiana.
"Guys can make a good living sooner than what it was two decades ago, three decades ago," Alford said. "We've had our share of some very good one-and-dones."
The Associated Press contributed to this report.